IN A NUTSHELL:It's not fluttering: it's swinging, and it only does so when the astronauts handle it or touch it. Moreover, the way it swings is different from how a flag swings on Earth and actually proves that the footage was shot in a vacuum.

THE DETAILS: In the TV and film footage of the lunar landings, the American flag sometimes moves as if it had been blown by a sudden gust of air. That, of course, is impossible on the airless Moon. Therefore, according to conspiracy theorists, this proves that the moonwalk footage was faked in a movie studio.

One might ask why the movie set used for the most important and complex fakery of the twentieth century would be so ridiculously shoddy as to have drafts, or why the people in charge of the hoax would be so pathetically dumb as to leave such glaring and revealing mistakes in the final product, but never mind. There's a simple explanation for the apparently strange behavior of the flag.

If you examine the Apollo footage, you find that the flag “flutters” only when an astronaut is shaking it, for example to drive its pole into the ground (Figure 6-9).

Figure 6-9. Flag oscillation in an Apollo TV transmission
while an astronaut drives its pole into the soil.

After the flag has been erected and left to settle, it doesn't move. Even its creases and wrinkles remain unchanged throughout the excursion, as shown by Figure 5-9 for Apollo 11. The alleged flutter is actually caused by the astronaut's handling of the flagpole, not by drafts.

Just after the astronauts let go of the pole, moreover, the flag has a very revealing behavior: it continues to oscillate stiffly and unnaturally for quite a while, differently from a flag on Earth, which comes to a standstill almost immediately. This happens because in the Apollo footage the flag is swinging in the vacuum of the lunar surface, so there's no air or atmosphere to brake its motion.

In 2008 the TV show Mythbusters put this to the test. An accurate replica of an Apollo flag was placed in a large vacuum chamber and its pole was turned, just like the astronauts did on the Moon. The same turning motion was applied while the chamber was filled with air and after the air had been extracted to produce a vacuum. The difference was quite evident: when the flag was in vacuum, it swung for much longer and in the drag-free way seen in the Apollo television record.

In other words, the anomalous motion of the lunar flags doesn't confirm the hoax theories: on the contrary, it confirms that the footage of the moonwalks was shot in a vacuum.

Figure 6-10. A flag is swung in a vacuum for Mythbusters (2008).

However, there’s a moment in the Apollo 15 footage, at 148:57:15 in mission elapsed time, in which the flag moves without (apparently) being touched by astronaut Dave Scott as he passes close to it. At first glance, it does indeed look as if Scott’s movement displaced some air which impinged on the flag. But before arguing that this is unquestionable evidence of fakery, other non-conspiratorial explanations should be considered.

For example, the apparently mysterious motion may have been due to actual contact between Scott's left arm and the flag. Due to the wide-angle setting of the camera lens, which exaggerates depth, Scott appears to be farther away from the flag than he actually is.

Another possible explanation is an electrostatic effect. As Scott walked on the lunar surface (which has a significant electrical charge of its own due to the ionizing effect of ultraviolet radiation and particles from the Sun), he may have accumulated a charge which attracted or repelled the flag in the same way that a plastic rod rubbed on a wool sweater attracts or repels hair or pieces of paper.

Since the almost-perfect vacuum close to the lunar surface is highly dielectric (i.e., essentially incapable of conducting electric currents), charge accumulation is easier than on Earth. Moreover, any attraction or repulsion of the flag is more conspicuous on the Moon than on Earth because on the Moon there's no air to slow the flag.

Another conceivable scenario is that the discharge from the astronaut's backpack sublimator might have created a momentary puff of gas that impinged on the flag. This would explain the fact that only the bottom corner of the flag moves.

Whatever the actual cause is, it can't be an air displacement on a movie set, because the same video sequence shows that the dust kicked by the astronaut's boots doesn't swirl, but falls sharply and neatly in an arc. This is typical of a vacuum and is not possible in air. The flag's slow and long-lasting oscillation is also consistent with a low-gravity vacuum environment.